Was in Radio Shack last night and found the 8GB sticks for $39.99 and the 4GB sticks for $24.99.
I know there is a clearance thread for Radio Shack but this looks to be a sale - possibly weekly.
http://www.radioshack.com/search/index.jsp?kwCatId=&kw=pro%20duo&origkw=pro%20duo&sr=1